A linear motor can be implemented using at least one electromagnet attracting a pole plate. Two forces in opposite directions are obtained by such a motor, either by using an electromagnet that attracts a pole plate, thereby moving either the pole plate or the electromagnet in a first direction depending on whether one or the other one of them is movable, and resilient return means acting in the opposite direction, which solution is unsuitable if it is desired to be able to control displacement in both directions, or else by implementing a pair of electromagnets in alignment, each attracting a pole plate placed facing it. The second solution leads to linear motors of considerable length. In addition, such motors do not make it possible to provide displacements along a plurality of axes, and assembling such motors that extend along different axes leads to an assembly that is particularly complex and bulky.
The displacement of the pole plate or of the electromagnet, depending on which one of them is a moving part, can be used for transmission to some other mechanical member. Naturally, the moving part is held statically either by mechanical guidance or by a resilient suspension. If it is held by a resilient suspension, the mass of the moving part serves, beyond the natural frequency of the suspension, as a reaction point for injecting the force.